Hidden wiring detector. X-ray for walls

When overhauling premises with a change in the wiring diagram, as well as when laying additional high- and low-current lines in the wall, a special device is required - a hidden wiring detector. It can also be useful in other situations, for example, to find a burned-out light bulb in a Christmas tree electric garland, or when detecting a power outage.

The principle of operation of the device

Metal and hidden wire detectors can use:

1. The effect of the appearance of an electrostatic field in the zone near the conductor (it occurs in any conductor, even if it is not energized).
2. The occurrence of an electromagnetic field when an electric current flows through a conductor with sufficient power.
3. A well-known method of a metal detector, when a magnetic field is induced around a massive ferromagnetic object.

With the electrostatic method of detecting conductors, the following occurs. An alternating current line, which is energized, forms a field that attracts magnetized particles to itself. If the distance to the source is relatively small (up to 30 ... 50 mm), then in the absence of external interference and screens (even a wall with high humidity can serve as them), then the emitted signal is easily captured and fixed in any way convenient for the user.

The reliability of the operation of such a hidden wiring detector will be determined by the power of the load on the network, which, judging by user reviews, should be at least 1000 W, as well as the presence of steel embedded structures in the walls (with the exception of stainless ones). However, if there is a building plan for a house or apartment, such details are easily recognized.

Unlike the previous method, an electromagnetic field is created even in the absence of an external load, because there is no interference in this case. The sensitivity of such a metal detector increases with increasing field strength (it will always be there if the electricity supply to the apartment is not turned off). The method is suitable for detecting hidden wiring in wooden buildings, but is not practical for reinforced concrete walls.

The magnetic method is the least reliable, since it reacts with certainty both to the bracket in the wall forgotten by the builders and to the self-tapping screw screwed there.

It is possible that all of the above possibilities can be implemented. Such combined instruments are called multi-detectors and are used primarily by professionals. The most popular are imported multi-detectors from the brands Bosch, Mastech, domestic Woodpecker, etc.

If it is only possible for trained radio amateurs to make multidetectors with their own hands, then simpler designs are quite affordable to assemble on their own.

How to find the wiring in the wall without a device?

Here we consider two methods for indicating hidden wiring, which do not require any additional equipment at all, except for the ubiquitous gadgets and the simplest devices from the arsenal of a home electrician.

In the first case, you will need a smartphone, in the functions of which there is an option "magnetic sensor". In order for this feature to work, you need to download the Metal Detector app. The sensor does not differ in particular accuracy, however, in order to determine the place where you should not drive a nail, or where the wire break is approximately located, it is quite suitable.

After downloading the program, it will begin to function immediately: when the smartphone approaches the place where the antenna is located, to the wall, the coordinates of the test site immediately appear on the indicator, as well as a diagram of the strength of the magnetic field induction in microtesla. The sensitivity of the scale is 0.01 μT (for comparison, a souvenir magnet attached to a refrigerator creates a magnetic field with an induction of 500 μT, and the intensity of the magnetic field from an alternating current wiring of ordinary frequency is 0.2 ... 0.3 μT).

Moving along the wall with the smartphone turned on, one can observe the increase and decrease in the magnetic field induction, and at a certain threshold, an audible signal will also turn on. The result is shown not only on the scale, but also in the center of the gadget screen.

A conventional probe screwdriver is also suitable for detecting hidden wiring; it is better if there is an advanced model, with a built-in amplifier and an audio signal generator. Such a screwdriver is used in the reverse mode: they touch the tip of the screwdriver with their hand, after which they slowly lead it along the investigated wall of the room. It uses the effect of capturing an electromagnetic pulse from a network that is under load, so when approaching the place where the wire is laid, the intensity of the light and sound signal will increase.

Do-it-yourself hidden wiring detector. Scheme

Any field-effect transistor VT of the KP 303 or KP 103 brand, which will be the main element of the circuit, can capture the electromagnetic field present in the wall (see figure). In addition, a simple SP telephone speaker with a resistance of 2 ± 0.1 kΩ is required for operation, and an ohmmeter Ω connected in parallel with the transistor (any compact arrow-type indicator can be used). The homemade device is powered by three AA batteries.

The body of the transistor itself is used as an antenna, and any microswitch can be used to turn on the device. If you pass the transistor case over the surface under study, then when the voltage is applied to the room, a signal with a frequency of about 50 Hz will be clearly heard in the speakers (which will increase with increasing intensity of the electromagnetic field), and the indicator needle will deviate from 0. It is better to assemble the device circuit in this way so that the transistor is in a metal case, one of the sides of which is open.

The polarity of the transistor connection does not matter, because it will only affect the direction of the arrow. The only limitation of this circuit is its low sensitivity, which will not allow it to be used for remote detection of electrical wiring. But almost anyone who has ever used an electric soldering iron can assemble such a device with their own hands.

Rating of the best hidden wiring detectors

Analyzing user reviews, you can arrange the top three as follows:

1. Signaling device for hidden wiring Woodpecker E121. It works according to the electrostatic principle, is light, compact and highly functional - it can track hidden wiring, its breakage, determine the phase and neutral wires in the household electrical network, check the grounding, etc. Woodpecker E121 is convenient to use, since the device moves directly over the surface under study. Disadvantage - to use the device in the network, there must be an operating voltage. Issue price - 1800 ... 2000 rubles.

1. Detector model Bosch GMS 120 Prof refers to the devices of the middle price category. It can determine the necessary parameters remotely when moving away from the object at a distance of up to 50…60 mm (with increasing distance, the error increases) for metal objects, and up to 100…120 mm for wood or plastic. Bosch GMS 120 Prof is powered by batteries and the accumulator supplied with the device. The accuracy of the determination is not affected by the humidity of the walls and the room, and the result can be recorded not only on a scale, but also by a corresponding mark on the wall. The cost of the device is 6000 ... 6200 rubles.

1. DSL-8220S Metal and Flush Wire Detector. Requires a supply voltage of 9 V, and runs on rechargeable batteries of the "Krona" type. In terms of its capabilities, it is similar to the Woodpecker E121 device, but differs in the possibility of using it also for indicating hidden objects made of non-metals and plastic. The case has a splash-proof design, the depth of detection of defects is up to 200 mm. At an affordable price - up to 1000 ... 1200 rubles.